Dr. Ryan Tewhey with a member of his lab. PHOTO COURTESY OF JAX

JAX scientists explain COVID virus and variants



By Ezra Sassman

[email protected]

BAR HARBOR — Although COVID-19 cases are falling across the country, the SARS-CoV-2 virus has mutated, developing variants preliminary studies have found to be more infectious than the original virus. At least one new variant, B.1.1.7, has shown up in Maine, after a test identified a positive case in Franklin County earlier this month. 

The Islander spoke with Jackson Laboratory professors Dr. Derya Unutmaz, M.D., and Dr. Ryan Tewhey, Ph.D., to discuss how viruses mutate, how new SARS-CoV-2 variant cases are diagnosed and how well vaccines protect against these new strains. 

It’s common for viruses to produce variants, and as Unutmaz explains, most mutations cause no significant changes to the “replication, infectibility, or life cycle of each virus.”  

Viruses can mutate around 19 or 20 times a yearTewhey said. “That’s just an inherent property of a virus and its life cycle. They’re designed to mutate much faster than humans or other large animals do.” 

Both professors clarify that some viral variants have a “fitness effect” that give them an evolutionary advantage. Tewhey says some fitness effects give viruses an increased ability to “transmit or infect individuals, which in turn gives it an advantage to spread in the population.” 

Three important new variants of SARS-CoV-2 include B.1.1.7, first identified in England; B.1.351, first identified in South Africa; and P1, first identified in Brazil. These specific lineages stand out from other variants because they each have a “fitness effect” that allows them to more efficiently infect humans. It is too early to know for sure, but researchers worry mutations might also offer new strains a certain degree of protection from vaccines. 

These variants are often more infectious because of a series of changes in Cov-2’s “S”-gene, which encodes for the spike protein. As Tewhey explained, “typically, it is mutations that fall in the spike protein that are driving these changes. We’re most closely monitoring [the spike protein] for new mutations because we know that’s how the virus docks onto human cells.” Unutmaz describes the virus’s spike protein as a “key” that can open up the “lock” of human cells. Any mutation that improves upon this “key” would allow for the virus to more easily enter and infect humans. 

Despite these troubling mutations, the overall picture of CoV-2 infections has steadily improved in the U.S. since last year’s peak. Here on Mount Desert Island, the news is even better: there have been no new confirmed cases of COVID-19 at the MDI Hospital in the past week. 

And it’s not just the original virus that would show up on tests: these new variants are also getting identified and counted.  

Tewhey explained that each diagnostic test analyzes three distinct areas in the viral genome. Even if one of these areas is different, the other two still offer enough information to recognize CoV-2. In fact, testing that does not detect the “S”-gene can help identify viral variants. When testing in the other two locations points to the CoV-2 virus, said Tewhey, “you can diagnose someone as positive based on those two, but then know [the case] might be a B.1.1.7. because it’s dropping out on the ‘S. 

Key mutations in SARS-CoV-2.
PHOTO COURTESY OF Jane Cha/JAX

When thinking about mutating viruses and vaccines, the yearly flu shot might come to mind. But the SARS-CoV-2 vaccine will require fewer adaptations. Tewhey explained that SARS-CoV-2 has fewer diverse variants than the flu.  

“The strains are small changes. It’s a bit easier to track in that regard.”  

Unutmaz also has reason for hope. “There are only a limited number of mutations [SARS-Cov-2] can accommodate to evade the immune system and still be fit enough to enter into human cells. It seems it has already reached saturation with recent mutations. We may need one additional vaccine for these, but [the mutations] may be the last Joker cards the virus currently has, he said. 

 Tewhey said that existing scientific infrastructure will enable the prompt creation of any necessary new vaccines. “Another really promising aspect is that some of the new vaccination technologies that have been developed, most notably Moderna and Pfizer, allow for rapid production of new variants. So, it’s just a matter of identifying that variant, programming it in, and testing it. It’s a much faster process than traditional methods. [Mutations are] less of a concern for CoV-2 because some of the vaccination methods are more amenable to quick changes.” 

Additionally, Tewhey points out vaccines are already showing high degrees of effectiveness against these new strains. “Right now, the main message is none of these variants have been shown to significantly impact the vaccine’s ability to neutralize the virus. That’s the promising data. There’s a slight reduction for some of them, but there’s a buffer built in. These vaccines work so well that we can afford that reduction. That’s the good news right now. With that being said, there is a lot of concern that additional variants could come along that might be able to bypass the vaccine.” 

Many statistics around COVID-19 present a simple binary of death versus recovery rates. But as Tewhey stresses, minimizing the total number of infections will also minimize the ability for virus to mutate.  

“One thing that’s important to point out is these mutations are random, and the more infections that occur and the more the virus is allowed to spread in the population, the more opportunities there are for mutations to accumulate, he said. 

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